1. Field of the Invention
The present invention relates to an observation device, and more particularly to a technology for providing both a macro optical system and a micro optical system in the same device.
2. Description of the Related Art
Conventionally, switching of the magnification of an observation device, such as a microscope, has been performed by switching the objectives attached to a revolver. However, it is difficult to implement the switching of magnifications having an extremely large magnification difference using only this method, i.e., by only switching objectives by means of a revolver. This is because the large magnification difference leads to a large difference between the focal lengths of the objectives, and it is difficult to put in and take out optical systems that have a large difference between their focal lengths while maintaining their compatibility.
In the market of observation devices such as microscopes, meanwhile, a large magnification difference tends to be desired. For example, when an observation is performed using a glass-bottom dish, a well plate, and the like, both an extremely low magnification enabling an observation of the entirety of an observation object and a high magnification enabling a detailed observation of the cell and the like of an observation object are used. In addition, in order to observe the entirety of the glass-bottom dish and of the well plate at one time, a reduction magnification (i.e., lower than a 1-fold magnification) is usually needed.
Japanese Patent Application Publications No. H5-232385, No. H9-211334, and No. 2002-148526 disclose a configuration in which the microscope comprises both a micro optical, system achieving a high magnification and a macro optical system achieving an extremely low magnification.
In these disclosures, however, since a macro optical system having a long focal length and a micro optical system having a short focal length are simply combined, it is difficult to actually make such a configuration.
In addition, nothing is done to avoid the occurrence of an illumination irregularity in the macro optical system or the micro optical system, which may occur when they share an epi-illumination optical system.